On Thursday, Foreign Policy magazine posted online a nine-page memo from Obama to Hillary Clinton, the US secretary of state, that linked the continuation of funding to US counterterrorism efforts in some of those countries.

"Everyone’s gotten a pass, and Obama has really completely undercut the law and its intent," Jo Becker, children’s rights advocacy director for Human Rights Watch, told the New York Times newspaper.

Of the six countries identified by the State Department as having used child soldiers in 2009, only Somalia and Myanmar were not granted an exemption. Myanmar receives no military aid from the United States, but the vulnerable Transitional Federal Government of Somalia receives significant assistance. In May 2009, the United States applied for an exemption from an United Nations' arms embargo on the country in order to provide Somalia with assault rifle, mortar and machine gun ammunition, and rocket-propelled grenades.

Al-Qaeda as justification

In the memo, signed by Obama, the White House called Yemen a "key partner" in the fight against al-Qaeda in the Arabian Peninsula (AQAP) and said that imposing the funding prohibition against Yemen "would seriously jeaopardise the Yemeni government's capability to conduct special operations and counterterrorism missions, and create a dangerous level of instability in the country and the region".

The apparently growing influence of American Muslim cleric Anwar al-Awlaki, identified by the United States as an AQAP leader, and the attempted December airliner bombing by Umar Farouk Abdulmutallab, a Nigerian who allegedly spent time with AQAP, have driven the assistance.

Though Yemeni law requires military recruits to be at least 18 years old, "credible reports" indicate children as young as 15 have entered the country's armed forces, while tribal militias mobilised by the government to fight Shia Houthi rebels in the north have recruited 14-year-olds, the White House memo says.

The memo goes into detail about the ways that Yemen has used US financial assistance: to buy spare parts for a C-130 transport plane and UH-1 helicopters, weapons and equipment for special forces charged with "hunting down" al-Qaeda, and fast patrol boats and floating piers for Yemen's navy and coast guard.

'Working to eliminate child soldiers'

For each exempted country, the White House memo states that the US government "is working ... to reduce and eliminate" the use of child soldiers. The document makes the argument that cutting off funding to the affected governments' militaries will make it harder to ultimately turn them away from recruiting youths.

In the case of Chad, the memo says that applying the 2008 law "would hinder the United States government's effort to reinforce positive trends," such as an effort to work with the United Nations to demobilise children in the army.

The memo also cites Chad's counterterrorism role. It says Chad "plays a critical role" hosting some 280,000 Sudanese refugees and is a US "partner" in the Trans-Sahara Counter Terrorism Partnership and "strongly supports" counterterrorism objectives.

In Sudan, where citizens will vote on possible secession between north and south in 2011, the US government currently funds military education for the Sudan People's Liberation Army (SPLA) - the southern Sudanese armed forces - and the memo states that prohibiting funding would "preclude the ability to deliver critical training necessary to professionalize the SPLA".

As of December, the memo says, the SPLA included around 1,200 children - boys and girls ages 12 to 17.

"Some of these children serve as combatants, and others, including those under 15 years old, serve a variety of functions, including as guards, porters, and cooks," the memo says.

The decision by Obama to waive penalties for some countries has exposed him to criticism from both human rights groups and Republicans.